Formation of overdeepened valleys

Overdeepened valleys and basins are commonly found below the present landscape surface in areas formerly affected by glaciations. This includes the European Alps, that were repeatedly glaciated by extensive foreland glaciers during the Pleistocene. An overdeepening is defined as a topographic depression below the fluvial base level that was excavated by glacial processes. Consequently, they act as primary sediment sinks in deglaciating landscapes. After their erosion, overdeepenings rapidly fill up with glacial, lacustrine and deltaic sediments until eventually, they are completely hidden under the modern landscape. The only visible marks in today’s landscape are several deep, elongated lakes that are not yet filled with sediments and that occur along Alpine valleys and its foreland. Lake Constance is, for example, the largest one of those remaining lakes.